A Smart Choice for Human Cytochromes P450 Phenotyping Assays
Drug-drug interaction can significantly impact drug safety and efficacy. Prediction of this risk of drug-drug interactions is a requisite in the development of a new drug candidate and the submission of the registration dossier. In vitro identification and measurement of the contribution of the major cytochrome P450 enzymes involved in the human metabolism of a new drug candidate, also called “CYP phenotyping”, helps predict the impact of co-administered drug, or perpetrator, on the pharmacokinetics of the new chemical entity, or the victim. Up until now, these studies are carried out using three common approaches:
- Correlation analysis
- Antibody or chemical inhibition
- Metabolism by recombinant human enzymes
Unfortunately, models such as correlation analysis provide no direct quantitative measurement of the contribution of each CYP in the metabolism of a drug. Models such as recombinant CYP450 enzymes are not fully representative of the liver enzyme profile. Not to mention that many chemical and antibody inhibitors lack sufficient specificity to enable confidence in results
To overcome the disadvantages of the current methodologies, a patented new in vitro drug development model was developed.
Silensomes™ are validated human pooled liver microsomes (HLMs) chemically and irreversibly inactivated for one specific CYP using mechanism based inhibitors (MBI).
Each Silensomes™ is available as cryopreserved, ready-to-use HLMs chemically knocked-out for one specific CYP activity (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, 3A4) with each showing high specificity and efficiency of their targeted CYP inhibition (>80%), and only minor impact (<20%).
The thaw and go format of Silensomes™ enables researchers to focus more on results and less on validating the level of CYP inhibitions. Silensomes™ are available now from Lonza for compound screening purposes and for regulatory validation.
Case Study: CYP3A4-Silensomes™
CYP3A4-Silensomes™ and its homologous control were incubated with different CYPspecific substrates.
- CYP3A4 mediated metabolism of testosterone, a pure CYP3A4substrate, was totally inhibited.
- More than 80% of CYP3A4-mediated metabolism of nifedipine and midazolam was inhibited. Residual metabolism of these substrates was inhibited by ketoconazole, revealing the CYP3A5 contribution.
- There was no impact on the other CYP activities tested.
|SIL200||Human hepatic CYP3A4-Silensomes™|
|SIL210||Human hepatic CYP1A2-Silensomes™|
|SIL220||Human hepatic CYP2A6-Silensomes™|
|SIL230||Human hepatic CYP2B6 Silensomes™|
|SIL240||Human hepatic CYP2D6-Silensomes™|
|SIL250||Human hepatic CYP2C8-Silensomes™|
|SIL260||Human hepatic CYP2C9-Silensomes™|
|SIL270*||Human hepatic CYP2C19-Silensomes™|
|SIL280*||Human hepatic CYP2E1-Silensomes™|
|SIL201||Human hepatic Control CYP3A4-Silensomes™|
|SIL211||Human hepatic Control CYP1A2-Silensomes™|
|SIL221||Human hepatic Control CYP2A6-Silensomes™|
|SIL231||Human hepatic Control CYP2B6 Silensomes™|
|SIL241||Human hepatic Control CYP2D6-Silensomes™|
|SIL251||Human hepatic Control CYP2C8-Silensomes™|
|SIL261||Human hepatic Control CYP2C9-Silensomes™|
|SIL271*||Human hepatic CYP2C19-Silensomes™|
|SIL281*||Human hepatic Control CYP2E1-Silensomes™|